Adjustable spring trip shank assembly

ABSTRACT

A self-restoring spring trip shank assembly of the type having a mounting element secured to a toolbar, a shank pivoted to the mounting element, and a spring acting between the mounting element and the shank to yieldably hold the shank in a working position. The spring acts on a multi-position reversible bracket secured to the shank so that by reversing the bracket the moment arm through which the spring force acts is varied and the force needed to pivot the shank upwardly is varied.

United States Patent Essex ADJUSTABLE SPRING TRIP SHANK ASSEMBLY DuaneArnold Essex, Des Moines, Iowa [7 3] Assignee: Deere & Company, Moline,Ill.

[22] Filed: March 3, 1971 [21] Appl. No.: 120,495

[72] Inventor:

[52] US. Cl. ..l72/265, 172/705, 248/15, 267/177 [51] Int. Cl. ..A01b61/04 [58] Field 01 Search ..267/l77; 16/130, 158, 190; 248/15; 172/261,264, 265, 307, 484, 497, 500, 657, 705-707, 710

[56] References Cited UNITED STATES PATENTS 3,098,529 7/1963 Wade et al..172/710 1 Oct. 24, 1972 Anderson ..248/1 5 Groenke 1 72/710 PrimaryExaminer-Robert E. Pulfrey Assistant Examiner-C. W. l-lanor Attorney-H.Vincent Harsha, Harold M. Knoth, William A. Murray, John M. Nolan andRaymond L. Hollister ABSTRACT A self-restoring spring trip shankassembly of the type having a mounting element secured to a toolbar, ashank pivoted to the mounting element, and a spring acting between themounting element and the shank to yieldably hold the shank in a workingposition. The spring acts on a multi-position reversible bracket securedto the shank so that by reversing the bracket the moment arm throughwhich the spring force acts is varied and the force needed to pivot theshank upwardly is varied.

4 Claims, 5 Drawing Figures PATENTED 24 I97? 3 7 O0 038 I NVENTOR. DUANEA. ESSEX ADJUSTABLE SPRING TRIP SHANK ASSEMBLY BACKGROUND OF THEINVENTION The present invention relates generally to groundworkingagricultural implements, and more particularly relates to aself-restoring spring trip shank assembly such as that used on fieldcultivators and chisel plows.

Earth-working implements in which the tool shank is yieldably held inworking position by a spring force are generally well known and varyingtheories as to the ptimum shank deflection force have been developed.One theory adheres to a relatively small shank deflection force sinceactive shank action or a high frequency of vibration of the tool resultsin superior trash clearance and an easier pulling implement. A secondtheory favors a relatively large shank deflection force which provides amore aggressive action for the tool and holds the tool level until anobstruction is encountered.

SUMMARY OF THE INVENTION The principal object of the invention is toprovide a self-restoring spring trip shank assembly for earthworkingtools in which the force required to deflect the shank can be varied.

A more specific object of the invention is to provide a self-restoringspring trip shank assembly for earth working tools in which the momentarm through which the spring force acts to hold the shank in a workingposition can be varied so as to vary the force needed to deflect theshank upwardly.

Another object of the present invention is to provide a self-restoringspring trip shank assembly for earthworking tools in which the momentarm through which the spring force acts to retain the shank in a workingposition can be varied by the reversal of a spring bracket clamped tothe shank.

The above objects and additional objects and advantages will becomeapparent to those skilled in the art from a reading of the followingdetailed description of a preferred embodiment of the invention whentaken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a side elevation view of a spring trip shank assemblyconstructed in accordance with the principles of the present invention;

FIG. 2 is a sectional view taken substantially along the line 2-2 ofFIG. 1.

FIG. 3 is a top plan view of a portion of the shank illustrated in FIG.2;

FIG. 4 is a side elevation view of a portion of the assembly illustratedin FIG. 1 and illustrating the bracket in its alternate position; and,

FIG. 5 is a graphical representation of the loaddetlection curves forthe alternate positions of the bracket for the spring trip shankassembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,the spring trip shank assembly indicated generally by the numeral isillustrated as being mounted on a toolbar or support element l2 andconsists essentially of a mounting element 14, a shank 16, a clamp 18, atension link and a spring 22.

The mounting element 14 is formed as a channel member having legs 24 anda bight 26. A portion of the bight of the channel member has beenremoved near one end and the adjoining portion of the legs have beennotched to receive the lower rear corner of the toolbar 12. The mountingelement is retained in position on the toolbar 12 by a U-bolt 28 whichextends around the toolbar 12 and through apertures provided in thebight The mounting element extends upwardly and rearwardly from thetoolbar to an upper rear end portion 30 which extends rearwardly andslightly downwardly. The bight 26 of the upper rear end portion 30 ofthe mounting element 14 is apertured to receive a threaded rod 32forming part of the tension link 20. The head 34 of the rod 32 engagesthe upper surface of the bight 26 of the upper rear end portion 30 ofthe mounting element, and the lower surface of the bight of the upperrear end portion of the mounting element provides a spring-abuttingsurface for the coil spring 22.

The shank 16 is mounted between the legs 24 of the forward portion ofthe mounting element 14' for vertical pivotal movement by a pivot bolt36 and extends generally rearwardly and downwardly therefrom to a curvedportion which terminates in a forwardly directed earth-working tool 38.The sides of the shank 16 are provided with relieved areas 40 whichserve as a guide for the proper positioning of the clamp or bracket 18.

The clamp 18 is generally of inverted Y-shape when viewed in afore-and-aft direction with an upwardly extending central leg 42provided with an aperture 44 near its upper end and a pair of spaced,downwardly extending legs 46 provided with aligned apertures near theirlower ends. The inner portions of the legs 46 are slightly bulged as at48 and, when the clamp 18 is placed over the shank 16 with the legs 46straddling the sides of the shank 16, the bulges 48 extend into therelieved areas 40 and prevent the clamp from sliding on the shank. Aclamp bolt 50 extends through the aligned apertures in the legs 46 toclamp the legs 46 against the shank. When properly positioned on theshank 16, the clamp 18 is rearwardly of the pivot bolt 36 and below andslightly forwardly of the aperture provided in the upper rear endportion of the mounting element 14.

The lower end of the tension link consists of an inverted U-shapedanchor member 52 having an apertured bight through which the lower endof the threaded rod extends. The legs of the anchor member 52 are alsoapertured and secured to the clamp 18 by an anchor pin 54 which extendsthrough the apertures in the legsof the anchor member 52 and through theaperture 44 provided in the central upwardly extending leg 42 of theclamp 18. The pin 54 is retained in a centered position in the aperture44 by a washer 56 having a downwardly directed lip. The washer 56 isslidably mounted on the anchor member so that when lowered it preventsthe legs of the anchor member from spreading and the lip extends alongthe ends of pin 54. A nut 58 on the lower end of the threaded rod 32between the legs of the anchor member 52 serves to limit the lowerposition of the shank 16 and also to precompress the coil spring 22which encircles the tension link 20 with its opposite ends bearingagainst the spring-abutting surface on the upper rear end of themounting element and the washer 56. By bearing against the washer 56,the spring 22 retains the washer in its lower position.

For normal operation, the nut 52 is tightened a suffrcient amount so asthe point of abutment between the bottom of the washer 56 and the pin 54is about a horizontal through the pivot bolt 36 so that upon upwarddeflection of the shank 16 the path of the point of abutment is upwardlyand forwardly. The forward movement results in a decreasing lever ormoment arm which cooperates with the increasing spring force to requirea substantially constant or only slightly increasing force to move theshank upwardly.

When viewed from the side, the central, upwardly extending leg 42 of theclamp 18 is offset from the center of the clamp 18 in a fore-and-aftdirection and the aperture 44 is centered in the leg 42 in theforeand-aft direction so it also is offset from the center of the clamp.With the aperture offset, reversal of the clamp 18 on the shank 16, fromthe FIG. 1 position to the FIG. 2 position or vice versa, will vary themoment arm (the distance from the center of the pivot bolt 36 to thecenter of the pin 54) through which the force of the spring 22 acts toretain the shank 16 in its normal working position and will thus varythe action of the shank l6 and its associated tool 38.

When the offset aperture is in the forward position as in FIG. 1, theforce needed to move the shank upwardly is relatively small as can beseen from curve a in FIG. wherein the amount of deflection of the shankfrom its normal position is plotted on the axis of ordinates and thecorresponding force on the tool 38 is plotted on the axis of abscissus.As can be seen from curve a, a relatively small force on the tool 38results in initial deflection of the shank. This provides high shankaction or a high frequency of vibration of the tool which results insuperior trash clearance on an easy pulling implement.

When the offset aperture is in the rear position as in FIG. 2, the forceneeded on the tool 38 to move the shank 16 upwardly is relatively highas can be seen from curve b in FIG. 5. The higher deflection force holdsthe tool level until an obstruction is encountered and thus gives a moreaggressive action for the tool 38.

Although only a single embodiment of the invention has been describedand illustrated, various modifications within the spirit and scope ofthe invention will be apparent to those skilled in the art and theseobvious modifications can be made without departing from the underlyingprinciples of the invention.

Iclaim:

l. A ground-working implement comprising: a support element; a mountingelement having a lower forward end secured to the support element andextending upwardly and rearwardly therefrom to an upper rear end havinga centrally apertured plate with a downwardly directed spring-abuttingsurface; a tool shank having a forward end connected to the lowerforward end of the mounting element for vertical pivotal movement andextending rearwardly therefrom; a

reversible bracket releasably secured to the shank rearwardly of theconnection between the shank and mounting element and below thecentrally apertured late' the bracket having an upward] directed aerured ear offset from the center of the racket in a ongitudinaldirection; tension link means having an enlarged upper end abuttingagainst the upper surface of the apertured plate and extendingdownwardly through the aperture to a lower end having a pair of spacedapertured legs positioned on opposite sides of the ear; a pin extendingthrough the apertured legs and ear to secure the tension link means tothe bracket; a washer having downwardly directed lip means slidablymounted on the lower end of the tension link means with the lip meansextending alongside the ends of the pin to prevent displacement of thepin; and coil spring means encircling the tension link means andcompressed between the spring-abutting face and the washer.

2. The implement set forth in claim 1 wherein the sides of the shank areprovided with relieved areas to receive the bracket so that, uponreversal of the bracket, the bracket is secured to the shank in theexact same location.

3. The implement set forth in claim 2 wherein the bracket is of invertedY-shape when viewed in a foreand-aft direction, each leg is apertured ina lateral direction, the lower legs are positioned along the sides ofthe shank in the relieved areas, a clamp bolt extends through theapertures in the lower legs and clamps the legs against the sides of theshank, and the pin extends through the aperture in the upper leg. I

4. A ground-working implement comprising: a support element; a mountingelement having a lower forward end secured to the support element andextending upwardly and rearwardly therefrom to an upper rear end having.a centrally apertured plate with a downwardly directed spring-abuttingsurface; a tool shank having a forward end connected directly to thelower forward end of the mounting element for vertical pivotal movementand extending generally rearwardly therefrom; a bracket-receivingrelieved area provided in each side of the shank in a positionrearwardly of the pivotal connection between the shank and mountingelement and forwardly of the center of the apertured plate; a brackethaving a pair of downwardly directed and laterally apertured legsmounted on the shank with the legs positioned along the sides of theshank in the relieved areas; a releasable clamp bolt extending throughthe apertures in the legs of the bracket clamping the legs of thebracket against the sides of the shank; the bracket having an upwardlydirected ear offset from the center of the bracket in a longitudinaldirection; laterally projecting abutment means carried by the ear;tension link means having an enlarged upper end abutting against theupper surface of the apertured plate and extending downwardly throughthe aperture to a lower end releasably secured to the laterallyprojecting abutment means; and coil spring means encircling the tensionlink means and compressed between the spring-abutting face and thelaterally projecting abutment means; the parts being so arranged andconstructed so that by reversing the bracket the car will be offset inan opposite direction and the moment arm through which the force of thespring acts is varied with a resultant variation in the force needed topivot the shank upwardly.

1. A ground-working implement comprising: a support element; a mountingelement having a lower forward end secured to the support element andextending upwardly and rearwardly therefrom to an upper rear end havinga centrally apertured plate with a downwardly directed spring-abuttingsurface; a tool shank having a forward end connected to the lowerforward end of the mounting element for vertical pivotal movement andextending rearwardly therefrom; a reversible bracket releasably securedto the shank rearwardly of the connection between the shank and mountingelement and below the centrally apertured plate; the bracket having anupwardly directed apertured ear offset from the center of the bracket ina longitudinal direction; tension link means having an enlarged upperend abutting against the upper surface of the apertured plate andextending downwardly through the aperture to a lower end having a pairof spaced apertured legs positioned on opposite sides of the ear; a pinextending through the apertured legs and ear to secure the tension linkmeans to the bracket; a washer having downwardly directed lip meansslidably mounted on the lower end of the tension link means with the lipmeans extending alongside the ends of the pin to prevent displacement ofthe pin; and coil spring means encircling the tension link means andcompressed between the spring-abutting face and the washer.
 2. Theimplement set forth in claim 1 wherein the sides of the shank areprovided with relieved areas to receive the bracket so that, uponreversal of the bracket, the bracket is secured to the shank in theexact same location.
 3. The implement set forth in claim 2 wherein thebracket is of inverted Y-shape when viewed in a fore-and-aft direction,each leg is apertured in a lateral direction, the lower legs arepositioned along the sides of the shank in the relieved areas, a clampbolt extends through the apertures in the lower legs and clamps the lEgsagainst the sides of the shank, and the pin extends through the aperturein the upper leg.
 4. A ground-working implement comprising: a supportelement; a mounting element having a lower forward end secured to thesupport element and extending upwardly and rearwardly therefrom to anupper rear end having a centrally apertured plate with a downwardlydirected spring-abutting surface; a tool shank having a forward endconnected directly to the lower forward end of the mounting element forvertical pivotal movement and extending generally rearwardly therefrom;a bracket-receiving relieved area provided in each side of the shank ina position rearwardly of the pivotal connection between the shank andmounting element and forwardly of the center of the apertured plate; abracket having a pair of downwardly directed and laterally aperturedlegs mounted on the shank with the legs positioned along the sides ofthe shank in the relieved areas; a releasable clamp bolt extendingthrough the apertures in the legs of the bracket clamping the legs ofthe bracket against the sides of the shank; the bracket having anupwardly directed ear offset from the center of the bracket in alongitudinal direction; laterally projecting abutment means carried bythe ear; tension link means having an enlarged upper end abuttingagainst the upper surface of the apertured plate and extendingdownwardly through the aperture to a lower end releasably secured to thelaterally projecting abutment means; and coil spring means encirclingthe tension link means and compressed between the spring-abutting faceand the laterally projecting abutment means; the parts being so arrangedand constructed so that by reversing the bracket the ear will be offsetin an opposite direction and the moment arm through which the force ofthe spring acts is varied with a resultant variation in the force neededto pivot the shank upwardly.